BRAZIL NUT TREE IN CEYLON. 427 



Young bases his decision on the characters of the pyxidium, 

 which might be expected to be more constant than those 

 abeady referred to. Accordhag to Mers' descriptions, the 

 pyxidium of B. excelsa is 6 in. long and 5 in. in diameter, with 

 a smooth, paHsh, lenticellated bark, which does not crack and 

 fall off ; the calycary zone, | in. below the apex, is 3 in. in 

 diameter ; the opercular zone, 8 lines (16 mm.) in diameter, 

 is contracted within into a depressed concave mouth, 6 lines 

 (12 mm.) in diameter ; the operculum is cylindrical, 5 lines 

 (10 mm.) broad, 5 lines (10 mm.) high, round and umbilicated 

 at the summit, and falls out ivhen the columella ivithers. The 

 pyxidium of B. nohilis is globular, 4-4| in. in diameter, with 

 a much thicker, rougher, darker, and more cracking resihent 

 bark, 3 lines (6 mm.) thick ; the endocarp is 4 lines (8 mm.) 

 thick, subosseous ; the inconspicuous calycary zone is 9-12 lines 

 (18-25 mm.) below the summit ; the upper zone, 6 lines 

 (12 mm.) in diameter, has a sharp edge, concave and widening 

 inwards ; the operculum, of the same diameter, rises little 

 above the mouth, is pulvinately depressed, radially sulcated, 

 shortly umbonate at the apex, and remains loithin the pyxidium 

 when the columella withers. 



Miers' figures show the pyxidium of B. excelsa more or less 

 lemon-shaped, i.e., elongated oval, with a prominent swelHng, 

 bounded by the well-defined calycary zone, at the apex. Its 

 bark is 4 mm. thick, and the endocarp 18 mm. thick, but the 

 specimen was evidently immature, and it is probable that the 

 endocarp would have contracted on ripening. The pyxidium 

 of B. nohilis is shown as globose, somewhat flattened at the 

 poles, without any swelling at the apex. The operculum of 

 B. excelsa projects as a subcylindrical column above the apex 

 of the pyxidium, and the opercular orifice has almost vertical 

 sides, or is slightly contracted inwards. Oil the other hand, the 

 operculum of B. nohilis is situated within the opercular orifice, 

 and is conical, with a small acute umbo which scarcely projects 

 beyond the opening, while the walls of the opercular orifice 

 are strongly oblique, so that it widens inwards to double its 

 external diameter. 



The photographs of B. nohilis given by Young exhibit the 

 same type of pyxidium as that figured by Miers, both with 



6(8)13 (55) 



